WordPress 'user_search_columns' Filter

/*NOTE:  The $search_string and $wp_user parameters that are in the filter's documentation are not getting passed to my callback*/
function my_plugin_user_search_columns($search_columns) {
    array_push($search_columns, 'company_name'); // 'company_name' is a value in the `wp_usermeta`.`meta_key` column

    return $search_columns;
}

add_filter('user_search_columns', 'my_plugin_user_search_columns');