Don't use MacKeeper. It is a malware. It does more harm than any good. See here --> https://discussions.apple.com/docs/DOC-3036
Don't install any applications like CleanMyMac 3 etc which is same like MacKeeper. There are lots of dangerous cleaning applications out there.
Get rid of Norton as well. You don't need these security applications on your Mac. Mac is almost invulnerable to viruses out there as long as you do regular software updates. These anti virus application may slow down your Mac by running constantly in background.
Now download and install this AntiMalware application and do a scan with --> https://www.malwarebytes.org/antimalware/mac/
Malwarebytes Anti Malware is the best one out there which can remove malware and adwares from your Mac.
Do not use any cleaning applications. These applications may remove system files which may make situation worse. You don't need to use any cleaning applications. Mac does that automatically.
However you can run Disk Utility to fix corrupted system files, fix permissions etc.
Go to Applications> Utilities folder and open Disk Utility. In Disk Utility, select your harddisk in left column (the first one in the list will be your hard disk), thenRepair Permission. After that click Verify Disk and if asked to repair, click Repair Disk.
If you are using latest Mac OS X El Capitan, then you will not see Repair Disk option in Disk Utility. Instead click First Aid button and run it. Repair if asked.
If you really want to manually clean caches and temporary files, then you can use Onyx --> http://www.macupdate.com/app/mac/11582/onyx
Onyx is the one of the highly rated cleaning tool out there, which is also FREE.
If you have any questions or would like any additional information, please let me know.