There is a spacecraft on an initial orbit. There is a target orbit. The Keplerian elements are given for the orbits.

The problem is: when and what $\Delta V$ to apply to the SC to move it to the target orbit in the optimal way (with minimum fuel consumption). Impulsive maneuvers are considered.

The problem would be easier, if we know the target point (i.e rendezvous problem), in this case I could solve the Lambert problem. What to do in my case (when any point of target orbit may be chosen)?