Advertiser has given me DFP's code as a third party code to display creatives, How can I track clicks for this campaign

Question

The advertiser has given me the standard as publishing code by DFP as a third party code to display their ads. I have created a line item and the creative is showing in the display area, what I want here is to click tracks on this creative. Help me out with this guys

The sample code is :

<script type='text/javascript' src='http://partner.googleadservices.com/gampad/google_service.js'>
</script>
<script type='text/javascript'>
GS_googleAddAdSenseService("ca-pub-xxxxxxxxxxxxxxxx");
GS_googleEnableAllServices();
</script>
<script type='text/javascript'>
GA_googleAddSlot("ca-pub-xxxxxxxxxxxxxxxx", "abc-728x90");
</script>
<script type='text/javascript'>
GA_googleFetchAds();
</script>
<!-- Express-728x90 -->
<script type='text/javascript'>
GA_googleFillSlot("abc-728x90");
</script>