What kind of IR sensor that detects at 25 cm are you talking about ? A IR temperature sensor ? So you want a IR temperature sensor (non-contact temperature sensor or pyrometer) for 3 to 4 meters range ?
You could try a thermal imaging camera with OpenCV recognition software. With a computer of course, that is not for an Arduino.
There are industrial pyrometers that can measure something a few meters away, but they cost above 1000 dollars. I don't know if there is a cheap sensor that can be connected to an Arduino. Flir has a number of different types, but I can't find a cheap sensor for longer range. I found this guy, but I can't find a way to contact him.