I do some research,and change to code to:
$data = array(
'name' => $field_53, // from name aka User/Client Name
'email' => $field_64, // from email aka User/Client Email
'phone' => $field_65, // phone number aka User/Client Phone Number
'subject' => $field_52, // test subject, aka Issue Summary
'message' => $field_50, // test ticket body, aka Issue Details.
'ip' => $_SERVER, // Should be IP address of the machine thats trying to open the ticket.
//'topicId' => 'serial_number', // the help Topic that you want to use for the ticket
//'Agency' => '58', //this is an example of a custom list entry. This should be the number of the entry.
//'Site' => 'Bermuda'; // this is an example of a custom text field. You can push anything into here you want.
//'attachments' => array()
);
It look like something get better, but I still get Unable to create new ticket: validation errors: user: Incomplete client information 20: subject is a required field * Error, and I am sure that in the webhook data, $field_52 do have data.