How do I define type of returned object based on selected fields?

// Example implementation of clientSelect
const clientSelect = {
   a: true,
   b: true,
   c: true
}

export const getClientById = async (
  clientId: number,
  select?: Prisma.ClientSelect
) => {
  return await prisma.client.findFirst({
    select: select || clientSelect,
    where: {
      id: clientId,
    },
  });
};

const myClient = getClientById(333, { a: true })

// I want TypeScript to understand that myClient contains a and doesn't contain b and c