Is there a URL that can open a contact search?
You can do this via full text search which gives you slightly different results than contact, but might meet your needs. If you are logged in to the demo server,check:

http://d45.demo.civicrm.org/civicrm/contact/search/custom?csid=15&amp;reset=1&amp;text=joe&amp;table=Contact&amp;force=1