Include all custom post types in front-end search results. Post types which have been set to be excluded from search will not be displayed.

include-post-types-in-search.php

<?php
add_action( 'pre_get_posts', 'prefix_include_cpts_in_search' );
/**
* Include custom post types in search results.
*
* Custom post types are not included in the default WordPress search
* functionality. This code will add them to all front-end searches.
*
* @author FAT Media, LLC
* @link   http://youneedfat.com
*/
function prefix_include_cpts_in_search( $query ) {

	// Do nothing if we're in the admin or not on a search query.
	if ( is_admin() || ! $query->is_search ) {
		return;
	}

	// Get all the post types which aren't excluded from search.
	$post_types = get_post_types( array( 'public' => true, 'exclude_from_search' => false ), 'objects' );
	$searchable_types = array();

	// Get the names of the searchable post types.
	if ( $post_types ) {
		foreach ( $post_types as $type ) {
			$searchable_types[] = $type->name;
		}
	}

	// Set up the query.
	$query->set( 'post_type', $searchable_types );

	return $query;
}