How to offset panTo in google maps

How to offset panTo in google maps

How can I offset the panTo function? When a marker is clicked I would like
to panTo it, but not place the marker in the center of the screen.
I would like to offset it (both x and y) by a desired % of the screen
width and height.
google.maps.event.addListener(marker, 'click', function() {
map.panTo(loc);
});
Thanks