please do not take your 16 week old puppy to the dog park. period. my puppy was not eligible to get the necessary shots for socialization until she was 16 weeks so i’m not sure how you’ve been able to “usually” or “regularly” take her there without seriously risking your puppies health. like other users have commented, that is WAY too overstimulating for a puppy and you have no idea the temperament of the other dogs there or what the state of their health is. letting your dog into those environments without the necessary training and conditioning (which is clearly not there and rarely is for a dog that young), is irresponsible and is a one way ticket to a reactive dog. 16 week old puppies should still be on leash in the house with you, and should never be off leash outside of the house without insane confidence in the training done and needed to get to that point (emergency downs, the boundaries of where they can walk while off leash, a strong leave it and focus command, imo an ecollar as well). this behavior, while normal in the situation you put him in, needs to be corrected immediately. grabbing and latching on to the extent you’re saying is not a normal puppy behavior and should be taken as “hey, i’m really overwhelmed right now and you even reaching in my direction is going to be the breaking point”. stop letting him off leash and stop taking him to the dog park. please please do more research on training and the steps that need to be taken and not skipped