I need an intellectual property clause that will protect my intellectual property as a consultant

I need to create Intellectual Property clause. As a freelance consultant I am often asked to sign contracts that assign intellectual property to my clients. Part of my business function requires me to use proprietary software that I have had built, trade secrets and other developed means and methods. I need a clause that can be inserted into any contract to replace the clients clause that will only assign documents and work product so that I retain all other intellectual property. Here is an example of a clients IP clause: Intellectual Property. The Parties acknowledge and agree that all right, title and interest in any documents, work product or intellectual property rights, including, without limitation, copyright, patents, designs, trade secrets and other rights associated with ideas, concepts, techniques, inventions, processes and works of authorship, that are created, made, conceived reduced to practice or authored by Consultant or its subcontractors in the course of performing, or in connection with or resulting from the performance of, the Consulting Services (collectively, the “Work Product”) shall be deemed to be “work made for hire” and shall immediately pass from Consultant to the Company upon Company’s payment of the Consulting Fees applicable to such Work Product. If and to the extent any Work Product cannot be deemed to be “work made for hire”, Consultant hereby irrevocably assigns to the Company, in each case immediately upon payment therefor being made by the Company and without additional consideration, all worldwide right, title and interest in and to such Work Product. Consultant shall take, or procure the taking of, all reasonable actions, including executing, or procuring the execution of, any necessary documentation, to effect such transfer of ownership, and shall ensure that any subcontractor who may be engaged by Consultant in connection with the performance of the Consulting Services is bound by the same obligations hereunder in respect of any Work Product which may be created by such subcontractor.