"Come, Holy Spirit"
"No one can say 'Jesus is Lord' except by the Holy Spirit." Every time we begin to pray to Jesus it is the Holy Spirit who draws us on the way of prayer by his prevenient grace. Since he teaches us to pray by recalling Christ, how could we not pray to the Spirit too? That is why the Church invites us to call upon the Holy Spirit every day, especially at the beginning and the end of every important action.
If the Spirit should not be worshiped, how can he divinize me through Baptism? If he should be worshiped, should he not be the object of adoration?
Source: Catechism of the Catholic Church (Vatican.va)