How to update a product price on a multi website environment using API (different price for different website)

For single website the following code working, but if I give only one website id in "website" array it is un selecting the product from other website.

    $client = new SoapClient('http://example.com/api/soap/?wsdl');
    $session = $client->login('exapmple*', 'exapmple');
    $result = $client->call($session, 'catalog_product.update', array(
        'PRIN-SKU',
        array(
            'websites' => array(5),
            'price' => '100',
        )
    ));