using (var client = new Klaatu_UserClient())
{
    client.ClientCredentials.UserName.UserName = _configurationService.GetWebServiceUser();
    client.ClientCredentials.UserName.Password = _configurationService.GetWebServicePassword();

    var request = new Klaatu_UserRequest(new UserWebService.Inbound_DT { User = requestObj });

    // call service
    var response = client.Klaatu_User(request);
}