Hi Slobodan.
Please try this:
$params = array(
"Fields" => array("name", "state","Manager"),
"TypeName" => "Project",
"Id" => array ("TypeName"=>"Project", "Value" => "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxx")
);
$request[] = new SoapVar($params, SOAP_ENC_OBJECT, "RetrieveMessage", "http://clarizen.com/api");
$executeResponse = $client->Execute(array("request"=>$request));
Ophir