KeepAlive

Hello all

I'd like to set the Connection KeepAlive to 'Off' when  sending a soap 
request:

 $client = new SoapClient('XMLSelect.xml',
        array( 'compression' => SOAP_COMPRESSION_ACCEPT | 
SOAP_COMPRESSION_GZIP | 9,
         'login'    => $_SESSION['x'],
         'password' => $_SESSION['y'],
         'HAP'      => $_SESSION['z']));

Can anyone help me with the code? do i send it through as a soapheader and 
how?

Thank you all in advance

Mario