[WordPress] include author's name in query search

gistfile1.php

<?php
function custom_search_join( $join ) {
	global $wpdb;
	if( is_search() ) {
		$join .= " INNER JOIN $wpdb->users ON "
			. "$wpdb->posts.post_author = $wpdb->users.ID ";
	}
	return $join;
}
function custom_search_where( $where, $query ) {
	global $wpdb;
	if ( $query->is_search() ) {
		$where = preg_replace(
			"/\(\s*$wpdb->posts\.post_content\s+LIKE\s*(\'[^\']+\')\s*\)/",
			"($wpdb->posts.post_content LIKE $1) OR ($wpdb->users.display_name LIKE $1)",
			$where
		);
	}
	return $where;
}
add_filter( 'posts_join', 'custom_search_join' );
add_filter( 'posts_where', 'custom_search_where', 10, 2 );