Wireshark enables you to use the "contains" filter which searches for a specified string. This can be used to look for a particular website in conjunction with filtering for http or https. An example filter could be
http contains "http://www.wireshark.org";
This would filter for only packets on port 80 that contain that URL. Fiddling with the string you may get better results. This website has more information on the "contains" option http://www.wireshark.org/docs/man-pages/wireshark-filter.html under Search and Match Operators.