It is important to note that the information I provided is based on the knowledge available . At that time, no stable or long-lived isotopes of oganesson (element 118) had been discovered. As a result, the properties of oganesson, including the presence of antimatter within its protons and neutrons, have not been experimentally determined.
Antimatter is composed of antiparticles, which have the same mass as their corresponding particles but opposite charge. Protons and neutrons are composed of quarks, and there is currently no evidence or theoretical prediction suggesting that antiparticles would be present within their structure.
Therefore, until further scientific advancements are made or new discoveries are made regarding the structure of oganesson or any other element, it is not appropriate to assign a percentage or discuss the presence of antimatter within the protons and neutrons of oganesson or any other atom.