Hello,
I think when you described about wsdl address, then the easiest way for accessing the soapclient web service, is by using PHPNUSoap where you will have an easy way for performing the Soap Data Structure and Request in PHP. It provide the hub/proxy based method, so the function can be called just like this: $varSoap->Function() instead of $varSoap->send("Function"). That's it.
Let me know if you agree with the method.
Best Regards,
Khamid