According to Dr Sharib:-

"Al-Khabir is the One Who knows well and is fully acquainted with the intricacies
and the implications of the universe and the One from Whom nothing is hidden."
He says emulation of the name requires that one acquaint oneself well with
one's own inner kingdom - the kindom of the heart, mind and body. One should
save oneself from the pernicious influences besetting life, renouncing the
hidden evils in the heart, such as jealousy, malice, greed, dishonesty, lust,
cunning, craftiness and hypocrisy. One should refrain from following those
dictates of the heart which lead one astray.

Appropriate recitation can help in revealing the hidden secrets and can secure
deliverance if you are entangled in the net of an undesireable person.

see 'The 99 Most Beautiful Names of Allah' by Dr Zahurul Hassan Sharib

Some other references:

Al-Ghazali says: '(Al-Khabir) has the same meaning as 'Omniscient', yet when
knowledge ['ilm] is related to hidden secrets it is called awareness [khibra], and
the one who possesses it is 'He who is aware [of everything]'.

(Al-Ghazali - The Ninety-nine Beautiful Names of God. Trans. Burrel/Daher: ITS: 1992.)

One of the innumerable and great kindnesses of God is when the spiritual guide
enables one travelling on the sufi way to become aware of his/her inner
kingdom. From this it becomes possible to understand that one has to manage
one's own inner world as a vice-regent, developing its 'ecology' to ensure that
all parts work together harmoniously. Each part benefitting other parts and all
working together for the whole. I remember Zahurmian emphasising the team
work required between the different elements. In modern parlance we may talk
about it as effecting a synergy.

Bismillah ir Rehman ir Rahim
The Well-informed, The Aware, The All-Cognisant One,
The Knowing, The Cognisant, The Totally Aware
Qur'an 6:18
He is the Irresistible, (watching)
From above over His worshippers:
And He is the Wise,
Acquainted with all things.
Wa Huwal-Qaahiru fawqa
'ibaadih: wa

(Qur'an 6:18 trans. Y. Ali)