Нашел решение кажется
$url = '
https://secure.softwarekey.com/solo/webservices/Xm...';
$client = new SoapClient($url);
$xmlr = new SimpleXMLElement("");
$xmlr->addChild('AuthorID', $authorID);
$xmlr->addChild('UserID', $userID);
$xmlr->addChild('UserPassword', $userPassword);
$xmlr->addChild('Email', $customerEmail);
$params = new stdClass();
$params->xml = $xmlr->asXML();
$result = $client->CustomerSearchS($params);