ServiceReference.OneClickForAppPortTypeV3Client client = new OneClickForAppPortTypeV3Client("OneClickForAppPortV3");
            using (new OperationContextScope(client.InnerChannel))
            {
                // Add a SOAP Header to an outgoing request
                MessageHeader aMessageHeader1 = MessageHeader.CreateHeader("PARTNER_ID", "http://oneclickforapp.dpag.de/V3", "APHMV");
                MessageHeader aMessageHeader2 = MessageHeader.CreateHeader("REQUEST_TIMESTAMP", "http://oneclickforapp.dpag.de/V3", DateTime.Now.ToString("ddMMyyyy-HHmmss"));
                MessageHeader aMessageHeader3 = MessageHeader.CreateHeader("KEY_PHASE", "http://oneclickforapp.dpag.de/V3", 1);
                MessageHeader aMessageHeader4 = MessageHeader.CreateHeader("PARTNER_SIGNATURE", "http://oneclickforapp.dpag.de/V3",
                    sign("APHMV","1", "28PwuxGYAYeHqImJciYI5QtuQUcjuIme"));
                OperationContext.Current.OutgoingMessageHeaders.Add(aMessageHeader1);
                OperationContext.Current.OutgoingMessageHeaders.Add(aMessageHeader2);
                OperationContext.Current.OutgoingMessageHeaders.Add(aMessageHeader3);
                OperationContext.Current.OutgoingMessageHeaders.Add(aMessageHeader4);

                client.authenticateUser(new AuthenticateUserRequestType(){ password = "1", username = "2" });
            }