meloniq

Enhance the default WordPress admin search by including custom fields (post meta) in search results. 
This plugin seamlessly extends the post listing (edit.php) search functionality, allowing administrators to quickly find content based on values stored in custom fields.
It works out of the box with no configuration required—just activate and start searching. 
Especially useful for sites that rely heavily on custom fields, such as those built with ACF or other meta-based data structures.
Lightweight, efficient, and fully integrated with the native WordPress admin experience.

WP-Admin Search Post Meta

Search WordPress admin posts by custom fields (post meta) directly from the default search.

websupporter

With the Plugin Profisearchform, you will be able to create search filter for your WordPress blogposts with ease! Just use the taxonomies and custom field values, you have already in use to create amazingly detailed search filters.
Features:
Fulltext Search – You can implement a fulltext search, which searches exactly the content, you want. Decide yourself, if you want to extend the search to specific custom fields, the title, the content and so on.
Select Box, Checkboxes, Radioboxes – Use these features, to place form fields, by which your visitor can restrict the search to specific terms or meta data values.
How to:
You just create a search filter by using simple drag & drop method. You can create your own search result templates and easily adjust the CSS of the outcome. After you have created a search filter, a shortcode gets generated, which you will be able to place on every page you want.
Go PRO:
With the premium version, you will have much more options:
<ul>
<li>You can place your filter as a widget everywhere on your page! </li>
<li>You can define the order, in which the results will appear. </li>
<li>You can highlight matching phrases!</li>
<li>You can use range sliders</li>
<li>You can include an order-by-field for your visitors</li>
<li>You can create min./max.-input fields</li>
<li>You can define how many posts per page will be shown</li>
<li>Instead of automatic search you can place search- & resetbuttons</li>
<li>You can restrict the search to a given term or meta data value</li>
<li>and much more…</li>
</ul>
Filter Custom Fields & Taxonomies is a five star WordPress plugin available on 
<a href="http://codecanyon.net/item/filter-custom-fields-taxonomies/6964843?ref=websupporter" title="WordPress Filter Plugin" rel="nofollow ugc">CodeCanyon</a>
More information: <a href="http://profisearchform.com" title="WordPress Filter" rel="nofollow ugc">WordPress Filter Custom Fields & Taxonomies</a>, 
<a href="http://profisearchform.com/video" title="Videos" rel="nofollow ugc">Video Tutorials</a>, 
<a href="http://profisearchform.com/help-faq" title="Filter Custom Fields & Taxonomies Help" rel="nofollow ugc">Help & FAQ</a>
Available languages: 
English, German, Serbian (thanks to <a href="http://www.webhostinghub.com" rel="nofollow ugc">webhostinghub</a>)

Filter Custom Fields & Taxonomies Light

Create search filter for your posts by using taxonomies or custom fields.

WP-Admin Search Post Meta vs Filter Custom Fields & Taxonomies Light