you entered a binding agreement with equal bargaining power

So your current employer could sue you for breaching it; though it's hard to assess the damage but the outcome would not be favorable to you in any way. You have to negotiate with your employer and maybe utilize the good impression of the Client to leverage the negotiation.

The non-compete clause with reasonable period is more than fair for the consulting firms like your employer. You'd never have the opportunities with the Client if it were not because of the firm.