search by two fields (help!)

Hey all! I love this plugin it works fine for me. But! I have custom field named: AREA
And in this field i put a numbers 100, 110 and ect… I think you know what i mean. So in custom fields search i want put two fields:
Maximum AREA
Minimum AREA

And if i put in minimum 100 and in maximum 150 search will be display items who have:
100, 101, 102 ….. and up to 150.

Ammm somthing like this:
http://www.knightfrank.be/index.cfm?template=portefeuille1.cfm

Search i want. What options i must choose to do this ?

http://ww.wp.xz.cn/plugins/wp-custom-fields-search/