James I think this is what you are talking about
'The Ancient of Days has three heads. He reveals himself in three archetypes, all three forming but one. He is thus symbolized by the number Three. They are revealed in one another. [These are:] first, secret, hidden 'Wisdom'; above that the Holy Ancient One; and above Him the Unknowable One. None knows what He contains; He is above all conception. He is therefore called for man 'Non-Existing' [Ayin]'" (Zohar, iii. 288b).
However, many passages in the Zohar talk about the unity and uniqueness of God, in the Jewish understanding of it, rather than the Trinity. One of the most common phrases in the Zohar is "raza d'yichuda "the secret of his Unity" which describes the Oneness of God as completely indivisible, even in spiritual terms.
The above phrase of the three heads, according to the kabbalists has extremely different connotations, as it is known that the Zohar is written in heavily coded terms according to Jewish tradition, and its true meaning is revealed only to the very righteous. However, the simple meaning of that above phrase, according to Jewish sources, has no relation at all to the Trinity. According to Judaism, God Himself is incomprehensible.
However, our relation to God is His Divine Presence. This may be comparable to a man in a room - there is the man himself, and his presence and relationship to others in the room. In Hebrew, this is known as the "Shechinah". It is also the concept of God's Name - it is His relationship and presence in the world towards us. The Wisdom (literally written as Field of Apples) in kabbalistic terms refers to the Shechinah, the Divine Presence. The Unknowable One (literally written as the Miniature Presence) refers to events on earth when events can be understood as natural happenings instead of God's act, although it is actually the act of God. This is known as perceiving the Shechinah through a blurry, cloudy lens. This means to say, although we see God's Presence (not God Himself) through natural occurrences also, it is only through a blurry lens, as opposed to miracles, in which we clearly see and recognize God's presence in the world. The Holy Ancient One refers to God Himself, Who is imperceivable. (see Minchas Yaakov and anonymous commentary in the Siddur Beis Yaakov on the Sabbath hymn of Askinu Seudasa, composed by the Arizal based on this lofty concept of the Zohar). This is the simple understanding of that phrase in the Zohar by Jews, however, as understood, there are many deeper and secret kabbalistic interpretations which are not open to the public.
According to the Jewish Encyclopedia, "This and other similar doctrines found in the Zohar are now known to be much older than Christianity, but the Christian scholars who were led by the similarity of these teachings to certain Christian dogmas deemed it their duty to propagate the Zohar."