How can I fix EMC problem over my PCB?
While I can't give you a definitive answer on what will fix your issue, three suggestions jump out immediately...


Treat LED+ and LED- like a differential pair.  I suspect this to be the source of most of the radiation, since it has the largest loops.  The current should flow from C14 through the LEDs, and then back to C14 as close as possible to the outward flow...preferably on the bottom side, under the LEDs and at least the center of the thermal pads.
Is L5 shielded?  If not, consider a shielded replacement.
Increasing the value of C14 will keep more RF current close to the switcher and out of the large LED loop.  Moving C14 down around L5, LED3, and LED4 will minimize your smaller switching loop.