WordPress exlcude post title like

I'm using woocommerce theme and with WP_Query i want to exclude results with post title LIKE "$postitle", how do i do this?

Here is my code

$args = array(
    'posts_per_page'=> $per_page,
    'orderby'       => $orderby,
    'order'         => $order,
    'no_found_rows' => 1,
    'post_status'   => 'publish',
    'post_type'     => 'product'

);


$products = new WP_Query( $args );