limit wordpress search to search by post title only

Wordpress search by post title

// Search by Post Title
	function search_by_title_only( $search, &$wp_query )
	{
	    global $wpdb;
	    if ( empty( $search ) )
	        return $search; // skip processing - no search term in query
	    $q = $wp_query->query_vars;
	    $n = ! empty( $q['exact'] ) ? '' : '%';
	    $search = '';
	    $searchand = '';
	    foreach ( (array) $q['search_terms'] as $term ) {
	        $term = esc_sql( like_escape( $term ) );
	        $search .= "{$searchand}($wpdb->posts.post_title LIKE '{$n}{$term}{$n}')";
	        $searchand = ' AND ';
	    }
	    if ( ! empty( $search ) ) {
	        $search = " AND ({$search}) ";
	        if ( ! is_user_logged_in() )
	            $search .= " AND ($wpdb->posts.post_password = '') ";
	    }
	    return $search;
	}
	add_filter( 'posts_search', 'search_by_title_only', 500, 2 );