Need advice on how I should fix my $params

I have a custom post type, BOOKS. It has several custom fields, namely; TITLE, AUTHOR, GENRE, RATING. I need advice on how to fix my code below so that only books that have the search word in the custom fields; title, author, genre; WITH EXACTLY the rating specified in my search form, gets displayed in the results?

I have made a custom search form; a text area that will search through the title, author, and genre; and a dropdown that will match the rating. The code in my params below only searches through the title, author, and genre. But I am now stumped in how to add the code for the rating.

This is how I visually imagined it: (title OR author OR genre) AND rating.

$params = array(
    'orderby' => $sortbooks,
    'limit' => 5,
    'search' => false,
    'where' => array(
        'relation' => 'OR',
          array(
             'key' => 'title',
             'value' => $searchvalue,
             'compare' => 'LIKE'
          );
          array(
             'key' => 'author',
             'value' => $searchvalue,
             'compare' => 'LIKE'
          );
          array(
             'key' => 'genre',
             'value' => $searchvalue,
             'compare' => 'LIKE'
          );
),
        array(
        'relation' => 'AND',
          array(
             'key' => 'rating',
             'value' => $ratingvalue,
             'compare' => '=',
             'type' => 'NUMERIC'
          ));

I would extremely appreciate your help and advice.

http://wordpress.org/plugins/pods/