2 KM coverage in radius need help

Hello
i need 2 KM coverage in radius client side using wlan card with outdoor 3 to 5 dbi omni antenna or directional but i need full 2 km coverage which hardware is best for me i have mt x86 based router which AP & antenna is best for me i have now 20 clients thanks

Normis plz reply me my clients are waiting please tell me which mikrotik hardware is best for me on this stage i need just 2km range in radius