It is up to them to express their wishes and reasons behind their call to an artist. They will discuss this directly with the artist and with all those involved in the initiative. The patrons also need to define the technical and administrative constraints such as the financial framework within which the artists will be working.
The patrons are responsible for the integration of the artwork within the community where it is lodged and accountable for the financial investment which will be required from the local people for the creation of the artwork.
Finally, the patron can't be a corporation insofar as establishing a dialogue and taking on such a responsibility is necessarily attributed to individuals. When the patrons act from within an organisation, they must have the approval of those who are legally responsible. The latter can associate themselves with the patrons, and thus contribute to the mediation process.