How to set MinValue for the WP Forms

Hey guys,
I am working on this site: http://wowdesigns.in/projects/nesties/

When you scroll down(footer) you can find the WPFORM(contact form)
I need to set the Min value to 3 for name field, could you please tell me how can I set that?

I want to force user to enter '3' values minimum in the name field.

Thanks