Settings - General - Auto Lock and Passcode Lock are where you need to head. However, these settings can all be restricted by the security policy of the profile on the phone, and may not offer much wiggle room. Many times, IT will use a feature that blocks access to VPN or mail if that security policy is not in place.

For Mark, the above is where you can tell a stock iPhone to never relock, no app needed.

Solutions beyond this will require jailbreaking the device, and using apps that override these security settings. I'd not recommend this path, since jailbreaks can be detected, and could lead to some serious issues for your wife if discovered. I personally wouldn't take the risk, though I also wouldn't use a work provided phone for anything personal.