use Symfony\Component\Notifier\Message\SmsMessage;
use Symfony\Component\Notifier\Bridge\ClickSend\ClickSendOptions;

$sms = new SmsMessage('+1411111111', 'My message');

$options = (new ClickSendOptions())
    ->country('country')
    ->customString('custom_string')
    ->fromEmail('from_email')
    ->listId('list_id')
    ->schedule(999)
    ->source('source')
    // ...
    ;

// Add the custom options to the sms message and send the message
$sms->options($options);

$texter->send($sms);