Design Patterns, override a method without need to re compile / relink

We are building a product that needs to run on production environments. We need to modify some of the functionality of a existing library. The existing library has class's and methods, we need to override 1 or more methods so that the caller uses our overriden methods instead of the original library.

OriginalLibrary

package com.original.library ;
public class OriginalLibrary {
    public int getValue() {
        return 1 ;
    }
    public int getAnotherValue() {
        return 1 ;
    }
}

Original Client

public class MyClient {
    private OriginalLibraryClass originalLibraryObject ;
    public MyClient () {
        originalLibraryObject = new OriginalLibraryClass() ;
        System.out.println(originalLibraryObject.getValue()) ;
        System.out.println(originalLibraryObject.getAnotherValue()) ;
    }
}

Output

1

2

Now, I need to change getValue() to return 3, instead of 1

Needed Output

3

2

package com.original.library.improved ;
    public class OriginalLibrary extends com.original.library.OriginalLibrary {
        public int getValue() {
            return 3 ;
        }
        public int getAnotherValue() {
            return super.getAnotherValue() ;
        }
}

If I do the above, I need to tell my Original Client to reorder and use my new com.original.library.improved jar file before com.original.library.

I am almost convinced that this is the most non intrusive way to launch my improved services over and above the OriginalLibrary. I would have preferred a solution where I need to tell the customer to just add my jar file, no need to recompile, relink your client code.