Which Person(s) of the Trinity were in Jesus? The doctrine of the Trinity teaches that God is one, and God is three (Father, Son, Holy Spirit.) From what I understand the Eternal Son came in human flesh, and we know that resultant man as Jesus of Nazareth. So would it be accurate to say God the Son was operating in a human body as "Jesus"? Were the Father and/or Spirit also in Him?

(I am, of course, looking for answers from a Trinitarian perspective.)
All three persons of the Trinity are in a perichoretic union.1 Hence, the Holy Spirit is called the Spirit of the Father2 and the Spirit of the Son,3 yet there still exist three persons of the Trinity.4
The Son said, “I and my Father are one,”5 to which the Jews picked up stones in order to stone him. He also told Phillip, “I am in the Father and the Father is in me.”6 By means of the Holy Spirit, the other Comforter,7 the Father and the Son would dwell in individual Christians.8
The Father is essentially and spiritually (obviously, not physically, as in the sense of a corporality) in the Son, as the Son is spiritually in the Father, and both are spiritually in the Holy Spirit, as there is a unity of essence. In such a manner, the Father is indeed in the Son, not only by a unity of will, as some assert. Thus, the apostle Paul wrote that “God was in Christ, reconciling the world unto Himself.”9

Footnotes
1 From the Greek word περιχώρησις
2 Matt. 10:20 cp. Mark 13:11
3 Gal. 4:6
4 Matt. 28:19
5 John 10:30
6 John 14:10–11
7 John 14:16
8 John 14:23
9 2 Cor. 5:19