Add Contact Custom Fields

$objects = Infusionsoft_DataService::query(new Infusionsoft_Contact(), array('Email' => $email));
        $contactId = $objects[0]->Id;
        $custom = array("_Friendsfirstname","_Friendsemailaddressforemailcontact","_Friendsmobilephonefortextcontact","_Howdidyoufindus","_Whatisyouragegroup");
        $contact2 = new Infusionsoft_Contact($contactId);
        $contact2->addCustomFields($custom);
        $contact2->_Friendsfirstname = $fr_name;
        $contact2->_Friendsemailaddressforemailcontact = $fr_email;
        $contact2->_Friendsmobilephonefortextcontact = $fr_phn;
        $contact2->_Howdidyoufindus = $findus;
        $contact2->_Whatisyouragegroup = $age;
        $contact2->save();