email hidden field

I have a form that has one message field and two hidden fields. I would like the hidden fields included in the message field on the process.php page so when I receive the email it has the hidden field info. I don't know how to go about this.

The hidden fields are client_id and client_name.

The process.php page is:

<?php

$mailto = '[email protected]' ;

$subject = 'Message/Comment' ;

$formurl = 'message.php' ;

$errorurl = 'error.php' ;

$thankyouurl = 'message_response.php' ;

$name = 'Company' ;

$email = $_POST['email'] ;

$message = $_POST['email_message_g'];

$dr_id = $_POST['dr_id'];

$web_title = $_POST['web_title'];

$http_referrer = getenv( 'HTTP_REFERER' );

if (!isset($_POST['email'])) {

header( 'Location: $formurl' );

exit ; }

$messageproper = $message;

mail($mailto, $subject, $messageproper, "From: "$name" <$email>nReply-To: "$name" <$email> nX-Mailer: chfeedback.php 2.01" );

header( "Location: $thankyouurl" );

exit ;

?>

Thanks in advance - Sam