The first thing you could attempt is to take a can of compressed air try to blow at an angle across the computers heat vents to try and remove as much debris as possible from the inside of the fan recesses without taking the computer apart. If this does not work you will have to take your laptop apart and look at the fan for any defects or obvious reasons the noise would be occurring during the laptops running. Last resort is to replace the fan or clean out the entire inside of the computer with a compressed air can. A great link for fan replacement can be found here: https://forum.ts.fujitsu.com/forum/viewtopic.php?t=46349