SQL Server :: Pass Stored Procedure Parameters Sometimes

Instead of dynamically building an sql to update data based on certain fields that are filled in, I would like to try and do it via a stored procedure I have three fields passing potentially passing to a stored procedure

myCommand.Parameters.AddWithValue("@Field1",
Field1.Text)

myCommand.Parameters.AddWithValue("@Field2",
Field2.Text)

myCommand.Parameters.AddWithValue("@Field3",
Field3.Text)

Stored Procedure accepts 3 parameters

@field1 nvarchar(20), @field2 nvarchar(20), @field3 nvarchar(20)

I want to be able to pass parameters in a variety of ways

field1, field2, field3
or
field1, field3
or
field2, field3

When I attempt thsi, it provides an error of a missing parameter when I do not supply all three. Is there any way to pass exclude parameters at times. The most important thing is that I do not want to update the field to a null when a parameter is not passed, I want it to exclude updating that field altogether