Louis

This WordPress plugin extends the default search to include meta (custom) fields
Major features in WP Search Include Meta Fields include:
<ul>
<li>No configuration necessary</li>
<li>Integrates with core search functionality</li>
<li>Doesn’t alter the database</li>
</ul>

WP Search Include Meta Fields

License: GPLv2 or later WordPress plugin to extend default search to include meta fields

greenturtlelab

This plugin is meant to used by some of <a href="http://greenturtlelab.com/" rel="nofollow ugc">Greenturtlelab’s</a> themes. This plugin registers 
required custom post types, taxonomies and meta fields to make theme able to work.
This plugin creates sub menu ‘GTL Components’ on wordpress admin panel under settings. Enable ‘Custom post types’ and ‘Taxonomies’ according to your requirement, You are good to go.

GTL Components

Register common custom post types, taxonomies and meta fields.

WP Search Include Meta Fields vs GTL Components