If you still want to try, the page with the frameset, i.e. frameset.php would look similar to this
<FRAMESET cols="20%, 80%">
<FRAME src="<?php echo $_GET['link']; ?>">
<p>Your browser doesn't support frames.
This frameset document contains this page:
<a href="<?php echo $_GET['link']; ?>">
And the link would be <a href="frameset.php?link=http://www.othersite.com/">
being the site that is supposed to be framed