Greetings Lon, Firstly I am not an Arian, but believe that there is one God the Father and that our Lord Jesus Christ is the Son of God. Firstly Jesus is not a mere man, He is the Son of God by birth, as God the Father is His father, and Mary is His mother Matthew 1:20-21, Luke 1:34-35. He is also the Son of God because He fully reflected the moral character of God, and He is the Son of God because He has been resurrected and glorified John 1:14, Romans 1:1-4.
Looking at your Ephesians 3:17-19 reference, but adding a bit more context:
Ephesians 3:14-19 (KJV): 14 For this cause I bow my knees unto the Father of our Lord Jesus Christ, 15 Of whom the whole family in heaven and earth is named, 16 That he would grant you, according to the riches of his glory, to be strengthened with might by his Spirit in the inner man; 17 That Christ may dwell in your hearts by faith; that ye, being rooted and grounded in love, 18 May be able to comprehend with all saints what is the breadth, and length, and depth, and height; 19 And to know the love of Christ, which passeth knowledge, that ye might be filled with all the fulness of God.
The concept is fairly clear, that God firstly filled Jesus with His Spirit, His character, His love, and Jesus is now able to fill us with the same. The source of all of this is from God the Father, but He has passed on this ability to Jesus, the Son of God.
Ephesians 4:13 (KJV): Till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ:
Kind regards
Trevor