WordPress - Add new user with custom role

functions.php

<?php
add_action( 'wp_loaded', 'add_role_client' );
function add_role_client() {
    add_role( 'client', 'Client', array(
        'read' => true
    )  );
}

index.php

<?php
$id_client = wp_insert_user( array(
    'user_login' => 'user_name',
    'user_pass' => 'strong_password',    
    'user_email' => '[email protected]',
    'role' => 'client'
) );