>>> import binascii
>>> binascii.hexlify('Привет!!!'.decode('cp866').encode('utf-16-be'))
'041f04400438043204350442002100210021'
>>>
>>> s = 'Привет!!!'
>>> ''.join(format(i, '02X') for i in s.encode('utf-16-be'))
'041F04400438043204350442002100210021'
>>>