You need to add an author parameter to the query that is creating $cust_loop. You didn’t post that part of your code but something like:
$cust_loop = new WP_Query( 'author=123' );
Or:
$cust_loop = new WP_Query( 'author_name=rami' );
Note: Both of those taken (almost) straight from the Codex paged for WP_Query.